A network service is a function performed by a communications network, such as data or telephony, and its associated resources in response to an interaction with one or more subscribers. For example, a telephony network resident service, such as call forwarding or voice mail access, can be invoked by a subscriber by dialing a special sequence of digits. Other network services may be directed at assisting a network owner with security, validation, and authentication. Adding or modifying a service requires changes to be made in the communications network.
Most conventional telecommunication networks are composed of interconnected switches and communication devices. These switches are controlled by integrated or imbedded processors operated by proprietary software or firmware designed by the switch manufacturer. Typically, the switch manufacturer's software or firmware must support all functional aspects of service processing, call processing, facility processing and network management. This means that when a network owner wishes to implement a new service or modify an existing service, the software of every switch in the network must be revised by the various switch manufacturers.
The fact that the network contains different switch models from different manufacturers requires careful development, testing and deployment of the new software. The time required to develop, test and deploy the new software is lengthened because the code size at each switch grows larger and more complex with each new revision. Thus, this process can take several years. In addition, this increased complexity further burdens the switch processors, increases the chances for switch malfunction, and may require the modification or replacement of the switch.
Moreover, the fact that multiple network owners depend upon a common set of switch manufacturers results in two undesirable situations that limit competition. First, a manufacturer's software release may attempt to incorporate changes requested by several network owners, thus preventing the network owners from truly differentiating their services from the services provided by their competition. This also forces some network owners to wait until the manufacturer incorporates requests from other network owners into the new release. Second, a switch software release incorporating a function as requested by one network owner to implement a new service can unintentionally become accessible to other network owners.
These problems have become intolerable as the demand for new network services has increased exponentially over the last five to ten years due to increased subscriber mobility, increased variety and bandwidth of traffic, dissolution of traditional numbering plans, more sophisticated services and increased competition. Thus, it is widely recognized that new network architectures need to incorporate a more flexible way of creating, deploying and executing service logic. In order to fully appreciate the novel architecture of the present invention hereinafter described, the following description of the relevant prior art is provided with reference to FIGS. 1-4.
Referring to FIG. 1, a logical representation of various switching architectures, including the present invention, is shown. A monolithic switch, which is denoted generally as 20, contains service processing functions 22, call processing functions 24, facility processing functions 26 and a switch fabric 28. All of these functions 22, 24, 26 and 28 are hard-coded, intermixed and undifferentiated, as symbolized by the group 30. Moreover, functions 22, 24, 26 and 28 are designed by the switch manufacturer and operate on proprietary platforms that vary from manufacturer to manufacturer. As a result, these functions 22, 24, 26 and 28 cannot be modified without the aid of the manufacturer, which slows down service development and implementation, and increases the cost of bringing a new service to market. The development of new and innovative services, call processing, data processing, signal processing and network operations are, therefore, constrained by the manufacturer's control over their proprietary switch hardware and software, and the inherent difficulty of establishing and implementing industry standards.
The service processing functions 22 are encoded within the monolithic switch 20 and only allow local control of this process based on local data contents and the number dialed. This local information is interpreted by a hand-coded process engine that carries out the encoded service function. The call processing functions 24 are hard-coded and provide call origination and call termination functions. This process actually brings up and takes down individual connections to complete a call. Likewise, the facility processing functions 26 are also hard-coded and provide all data processing relating to the physical resources involved in a call. The switch fabric 28 represents the hardware component of the switch and the computer to run the monolithic software provided by the switch manufacturer, such as Northern Telecom, Inc. The switch fabric 28 provides the physical facilities necessary to establish a connection and may include, but is not limited to, bearer devices (T1's and DS0's), switching matrix devices (network planes and their processors), link layer signal processors (SS7, MTP, ISDN, LAPD) and specialized circuits (conference ports, audio tone detectors).
In an attempt to address the previously described problems, the International Telecommunications Union and the European Telecommunication Standards Institute endorsed the ITU-T Intelligent Network Standard ("IN"). Similarly, Bellcore endorsed the Advanced Intelligent Network Standard ("AIN"). Although these two standards differ in presentation and evolutionary state, they have almost identical objectives and basic concepts. Accordingly, these standards are viewed as a single network architecture in which the service processing functions 22 are separated from the switch.
Using the IN and AIN architectures, a network owner could presumably roll out a new service by creating and deploying a new Service Logic Program ("SLP"), which is essentially a table of Service Independent Building Blocks ("SIBB") to be invoked during a given type of call. According to this approach, a number of specific element types inter-operate in conjunction with a SLP to provide services to network subscribers. As a result, any new or potential services are limited by the existing SIBBs.
The IN or AIN architecture, which is denoted generally as 40, logically separates the functions of the monolithic switch 20 into a Service Control Point ("SCP") 42, and a Service Switching Point ("SSP") and Switching System 44. The SCP 42 contains the service processing functions 22, whereas the SSP and Switching System 44 contain the call processing functions 24, facility processing functions 26 and the switch fabric 28. In this case, the call processing functions 24, facility processing functions 26 and the switch fabric 28 are hard-coded, intermixed and undifferentiated, as symbolized by the group 46.
The Service Switching Point ("SSP") is a functional module that resides at a switch in order to recognize when a subscriber's signaling requires more than simple routing based solely upon the number dialed. The SSP suspends further handling of the call while it initiates a query for correct handling of the call to the remote SCP 42, which essentially acts as a database server for a number of switches. This division of processing results in the offloading of the infrequent, yet time consuming task of handling special service calls, from the switch. Furthermore, this moderate centralization draws a balance between having one readily modifiable, heavy burdened repository serving the whole network versus deploying a complete copy of the repository at every switch.
Referring now to FIG. 2, a diagram of a telecommunications system employing an IN or AIN architecture is shown and is denoted generally as 50. Various customer systems, such as an ISDN terminal 52, a first telephone 54, and a second telephone 56 are connected to the SSP and Switching System 44. The ISDN terminal 52 is connected to the SSP and Switching System 44 by signaling line 60 and transport line 62. The first telephone 54 is connected to the SSP and Switching System 44 by transport line 64. The second telephone 56 is connected to a remote switching system 66 by transport line 68 and the remote switching system 66 is connected to the SSP and Switching System 44 by transport line 70.
As previously described in reference to FIG. 1, the SSP 70 is a functional module that resides at a switch in order to recognize when a subscriber's signaling requires more than simple routing based upon the number dialed. The SSP 70 suspends further handling of the call while it initiates a query for correct handling of the call. This query is sent in the form of SS7 messaging to a remote SCP 42. The Service Control Point 42 is so named because changing the database content at this location can alter the network function as it appears to subscribers connected through the many subtending switches. The query is sent through signaling line 72 to the Signal Transfer Point ("STP") 74, which is simply a router for SS7 messaging among these elements, and then through signaling line 76 to the SCP 42.
The Integrated Service Management System ("ISMS") 78 is envisioned as a management tool to deploy or alter services or to manage per-subscriber access to services. The ISMS 78 operates mainly by altering the operating logic and data stored within the SSP 70 and SCP 42. The ISMS 78 has various user interfaces 80 and 82. This ISMS 78 is connected to the SCP 42 by operations line 84, the SSP and Switching System 44 by operations line 86, and the Intelligent Peripheral ("IP") 88 by operations line 90. The Intelligent Peripheral 88 is a device used to add functions to the network that are not available on the switches, such as a voice response or speech recognition system. The IP 88 is connected to the SSP and Switching System 44 by signaling line 92 and transport line 94.
Now referring to FIGS. 2 and 3, the processing of a call in accordance with the prior art will be described. The call is initiated when the customer picks up the receiver and begins dialing in block 100. The SSP 70 at the company switch monitors the dialing and recognizes the trigger sequence in block 102. The SSP 70 suspends further handling of the call until service logic can be consulted in block 104. The SSP 70 then composes a standard SS7message and sends it though STP(s) 74 to the SCP 42 in block 104. The SCP 42 receives and decodes the message and invokes the SLP in block 106. The SLI interprets the SLP, which may call for actuating other functions such as database lookup for number translation, in block 106. The SCP 42 returns a SS7 message to the SSP and Switching System 44 regarding the handling of the call or otherwise dispatches messages to the network elements to carry out the correct service in block 108. At the conclusion of the call, a SS7 message is sent among the switches to tear down the call and call detail records are created by each switch involved in the call in block 110. The call detail records are collected, correlated, and resolved offline for each call to derive billing for toll calls in block 112. Call processing is completed in block 114.
The IN and AIN architectures attempt to predefine a standard set of functions to support all foreseeable services. These standard functions are all hard-coded into various state machines in the switch. Unfortunately, any new functions, which are likely to arise in conjunction with new technologies or unforeseen service needs, cannot be implemented without an extensive overhaul and testing of the network software across many vendor platforms. Furthermore, if a new function requires changes to standardized call models, protocols, or interfaces, the implementation of the service utilizing that function may be delayed until the changes are ratified by an industry standards group. But even as draft standards have attempted to broaden the set of IN and AIN supported functions, equipment suppliers have refused to endorse these draft standards due to the staggering increase in code complexity.
Referring now to FIG. 4, the process for generic service creation according to the prior art will be described. The network owner requests a new function involving a new service, new call state and new protocol in block 120. If a new call model is requested at decision block 122, a proposal must be submitted to the standards body and the network owner must wait for industry adoption of the new standard, which can take from one to three years, in block 124. After the new standard is adopted or if a new call model is not requested, as determined in decision block 122, the network owner must request and wait for code updates from each manufacturer to implement the new function, which can take from six to eighteen months, in block 126.
The network owner must test the new function and all previous functions for each manufacturer, which can take from one to three months, in block 128. If all the tests are not successful, as determined in decision block 130, and the cause of the failure is a design problem, as determined in decision block 132, the process must be restarted at block 122. If, however, the cause of the failure is a code problem, as determined in decision block 132, the manufacturer must fix the code in block 134 and the testing must be redone in block 128.
If all the tests are successful, as determined in decision block 130, and the manufacturer creates the service, as determined in decision block 136, the network owner must request a new service version from the manufacturer and wait for delivery of the tested version in block 138. If, however, the network owner creates the service, as determined in decision block 136, the network owner must create a new version of the service using a creation tool and iterate through unit testing to ensure that the new service works correctly in block 140. In either case, the network owner then performs an integration test to ensure that all previous services still operate properly in block 142. A system test must then be run to ensure proper coordination between the SCP and the switch in block 144. The network owner must then coordinate simultaneous loading of the new software release to all switches and SCP's in the network in block 146. The implementation of the new function is completed in block 148.
Referring now back to FIG. 2, other limitations of the IN and AIN architecture arise from having the call processing and facility processing functions, namely the SSP 70, operating within the switch. As a result, these functions must be provided by each switch manufacturer using their proprietary software. Network owners are, therefore, still heavily dependant upon manufacturer software releases to support new functions. To further complicate the matter, the network owner cannot test SSP 70 modules in conjunction with other modules in a unified development and test environment. Moreover, there is no assurance that an SSP 70 intended for a switch manufacturer's processing environment will be compatible with the network owner's service creation environment.
This dependancy of multiple network owners upon a common set of switch manufacturers results in two undesirable situations that limit competition. First, a manufacturer's software release may attempt to incorporate changes requested by several network owners, thus preventing the network owners from truly differentiating their services from the services provided by their competition. This also forces some network owners to wait until the manufacturer incorporates requests from other network owners into the new release. Second, a switch software release incorporating a function as requested by one network owner to implement a new service can unintentionally become accessible to other network owners. Therefore, despite the intentions of the IN and AIN architects, the network owner's creation, testing and deployment of new services is still impeded because the network owner does not have complete control of, or access to, the functional elements that shape network service behavior.
In another attempt to solve these problems, as disclosed in pending U.S. patent application Ser. No. 08/580,712, now U.S. Pat. No. 6,041,109, a Separate Switch Intelligence and Switch Fabric ("SSI/SF") architecture, which is referred to generally as 150 (FIG. 1), logically separates the SSP 70 from the Switching System 44. Now referring back to FIG. 1, the switch intelligence 152 contains the call processing functions 24 and facility processing functions 26 that are encoded in discrete state tables with corresponding hard-coded state machine engines, which is symbolized by circles 154 and 156. The interface between the switch fabric functions 158 and switch intelligence functions 152 may be extended through a communications network such that the switch fabric 158 and switch intelligence 152 may not necessarily be physically located together, be executed within the same processor, or even have a one-to-one correspondence. In turn, the switch intelligence 152 provides a consistent interface of simple non-service-specific, non-manufacturer-specific functions common to all switches.
An Intelligent Computing Complex ("ICC") 160, contains the service processing functions 22 and communicates with multiple switch intelligence elements 152. This approach offers the network owner advantages in flexible service implementation because all but the most elementary functions are moved outside the realm of the manufacturer-specific code. Further improvements may be realized by providing a more unified environment for the creation, development, test and execution of service logic.
As previously discussed, current network switches are based upon monolithic proprietary hardware and software. Although network switches can cost millions of dollars, such equipment is relatively slow in terms of processing speed when viewed in light of currently available computing technology. For example, these switches are based on Reduced-Instruction Set Computing ("RISC") processors running in the range of 60 MHz and communicate with each other using a data communications protocol, such as X.25, that typically supports a transmission rate of 9.6 Kb/s between various platforms in a switching network. This is extremely slow when compared to personal computers that contain processors running at 200 MHz or above and high end computer workstations that offer 150 Mb/s FDDI and ATM interfaces. Accordingly, network owners need to be able to use high-end workstations instead of proprietary hardware.